#include<bits/stdc++.h>
#define y1 Y1
#define fi first
#define endl "\n"
#define se second
#define PI acos(-1)
#define int long long
#define pb(x) push_back(x)
#define PII pair<int, int>
#define Yes cout << "Yes\n";
#define No cout << "No\n";
#define YES cout << "YES\n";
#define NO cout << "NO\n";
#define _for(i, a, b) for(int i = a; i <= b; ++i)
#define IOS ios::sync_with_stdio(false),cin.tie(0),cout.tie(0)
using namespace std;

const int N = 2e5 + 10;
int a[N];
int n, m;
string s;

signed main() {
	IOS;
	cin >> s;
	bool flag = true;
	
	int n = s.size() / 2;
	
	for(int i = 0; i < n; ++ i ) {
		if(s[i] != s[0]) {
			flag = false;
			swap(s[i], s[0]);
			swap(s[s.size() - 1], s[s.size() - 1 - i]);
			break;
		}
	}
	if(flag)cout << -1 << endl;
	else {
		cout << s << endl;
	}
	return 0;
}

